Just back from a road trip and noticed the shudder when accelerating up smooth freeway inclines only occurred with the transmission in overdrive. At first I had thought this might be an engine misfire but now it seems I have torque converter lockup shudder the 4R100 is known for. After browsing the Ford Truck Enthusiasts forum it looks like a transmission rebuild may be in my future?

Can you describe this better? I just took a 2000 mile trip and I had what seemed to be a momentary loss of power, maybe for a tenth of a second at cruising speed. It happened two separate times, both around 70ish MPH... like somebody turned off the horsepower and immediately flicked it back on. It makes me nervous and I've been trying to figure out what it was.

...what seemed to be a momentary loss of power, maybe for a tenth of a second at cruising speed. It happened two separate times, both around 70ish MPH... like somebody turned off the horsepower and immediately flicked it back on.

Precisely - a brief loss of power like a hiccup in the otherwise smooth flow of power to the drive axle. Google tells me this “shudder” is caused by the torque converter lock-up clutches slipping then engaging again. My symptom is infrequent and hard to reproduce. At first I thought it was an engine misfire from plug coils going bad but my scan tool showed no trouble codes. I did do a complete transmission fluid flush with Mercon V, to no avail. So for now I’ll continue driving, recheck proper fluid level and stay alert to any worsening of symptoms before deciding the proper diagnosis and repair. Too many questionable shops out there willing to just do a "black box" swap with an expensive Jasper reman unit.

I can wholeheartedly endorse John Wood Transmission, and, side bonus, they are in SE California (Holtville, off I-8; I see you are in SW Arizona).

There was an issue with my 4R100 when I bought my Chinook, and after hoping to have it worked on at several different places (but they said the noise was "normal" or some other reason didn't make me feel confident), I did some research for where would be a great place to go. I was willing to drive anywhere, basically, but for reasons I can't specifically remember, narrowed it down to one place in the Southeast (can't remember the fellow's name), and John Wood. Since I was in Arizona, the decision was obvious.

He's kind of "famous," and does transmission work for some race/offroad/"cool" rigs, so I wasn't sure how he'd feel about working on a "boring" RV, but he was enthusiastic, and said he likes matching the transmission to the task, whatever that might be, and I should bring it down. After a short test drive, he said he had a hunch what it might be, but we'd see when he got into it the next morning. By quitting time, my driveshaft was lying on the pavement under my Chinook and the transmission was on a gurney in the shop. Next morning he delved in, and sure enough, his hunch was right. (And no, "other shops," the noise was NOT normal!).

While he was "in there," I had him install a number of other beefed up parts, some of his own design. So it's now literally better than new.

His back story is that he worked for Ford for a decade, doing transmission rebuilds/repairs/warranty (back when the E4OD and 4R100 were current). He saw what the common flaws were and made suggestions, but they were kind of business as usual. So after ten years he struck out on his own, could do his design upgrades, and away he went (this is now decades ago).

He let me get up close and personal with the work, and explained each step (which I like). Everything made sense to me (and that's saying a lot, as automatic transmissions don't make sense to me in principal). A friend who also has an RV with a 4R100 later went and had the same work done (preventatively) and was equally happy with it.

In the end I was so glad I hadn't just gone for a run of the mill Ford rebuilt unit. I'm sure that would probably have worked fine, but I think what I got is better, and it cost less (although that wasn't the goal).

The only negative was that it was darned hot when I was there! (Try 108ºF) But it would have been great in the winter. It just worked out that I went in early May. Oh well, it was worth it (and the shop has a BIG ice machine )

BG

PS: Came back this morning to add that my transmission issue wasn't a shudder or anything like what you are describing - I just wanted to mention John Wood, especially since it sounds like you aren't far from his shop (although he does a lot of work on transmissions that are sent in/out from other shops as well).

Thanks for the rebuild reference, Blue~Go. Fortunately my transmission shudder was most likely due to my fluid being 1 pint low, so a simple fix. I probably got air in the system during my complete flush and it took a while to purge. It’s not trivial to set the correct level as it’s easy to get false high readings from oil splashed up in the dipstick tube.

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